The present application claims the priority of the commonly owned copending German patent application Serial No. 100 20 908.4 filed Apr. 28, 2000. The disclosure of the above-referenced German patent application, as well as that of each U.S. and foreign patent and patent application identified in the specification of the present application, is incorporated herein by reference.
This invention relates to chains in general, and more particularly to improvements in link chains of the type adapted to be utilized with advantage for transmission of torque between rotary parts of transmissions or the like. For example, link chains of the type to which the present invention pertains can be employed to transmit torque between driving and driven pulleys or sheaves in continuously variable transmissions (CVT) of the type employed in the power trains (i.e., between the engines or other prime movers and the wheel axles) of motor vehicles.
Link chains of the type to which the present invention pertains comprise composite chain links having packages or stacks of overlapping plate-like components. The components of neighboring links partially overlap and alternate with each other and are articulately connected to one another by coupling units which permit neighboring links to pivot relative to each other. The coupling units comprise pin-shaped elements extending through windows provided in the components of the respective pairs of links. The end faces of the pin-shaped elements engage the conical surfaces of flanges forming part of aforementioned (normally adjustable) pulleys or sheaves over which the link chain is trained, e.g., in the aforementioned continuously variable transmission of the type often employed in the power trains of motor vehicles.
A drawback of many presently known link chains is that they are noisy due to excessive play between neighboring parts such as the plate-like components of the composite links, the pin-shaped elements of the units which couple neighboring links to each other, and/or the flanges of the pulleys at least one of which drives the chain and at least one of which receives torque from the chain when the transmission is in use.
Another drawback of many presently known link chains is that they undergo rapidly progressing pronounced wear in actual use of the chains; this results in the generation of even more pronounced noise which is particularly undesirable when the link chain is employed in the power train of a motor vehicle.
A further drawback of conventional link chains is that their links cannot or are not likely to reassume predetermined starting positions relative to each other as well as that they cannot be readily confined to repeated pivotal movements to predetermined end positions. This can affect the accuracy with which a conventional link chain can transmit torque in a continuously variable transmission or the like.
Still another drawback of presently known link chains is that they are complex, that their useful life is rather short as well as that they are too expensive, especially if made to stand extensive periods of repeated use such as in the power trains of motor vehicles.
An object of the invention is to provide a link chain, particularly for use in CVT transmissions, which is simpler, safer and less expensive but more reliable (safer) than heretofore known link chains.
Another object of the invention is to provide a link chain the reliability and safety of which are less affected by manufacturing tolerances than those of conventional link chains.
A further object of the invention is to provide a link chain which can be assembled, installed in an infinitely variable transmission and/or otherwise manipulated in a manner much simpler than that known from conventional link chains.
An additional object of the present invention is to provide a link chain whose useful life is longer than that of presently known link chains and which is less prone to wear than conventional link chains.
Still another object of the invention is to provide novel and improved composite links as well as novel and improved articulate connections between the links of a link chain.
A further object of the instant invention is to provide novel plates or analogous constituents for use in composite links of a link chain which forms part of a continuously variable transmission.
Another object of the invention is to provide a novel and improved method of reducing the wear upon the links and/or other parts of the above outlined link chain.
An additional object of the instant invention is to provide a novel and improved method of providing a link chain which is quieter than heretofore known link chains.
Still another object of the invention is to provide a novel and improved combination of composite coupling units and composite links for use in the above outlined link chain.
A further object of the invention is to provide a novel and improved continuously variable transmission which employs one or more link chains of the above outlined character.
Another object of the invention is to provide a power train which can be utilized with advantage in a motor vehicle and embodies a CVT employing at least one link chain of the above outlined character.
An additional object of our present invention is to provide a link chain which is constructed and assembled in such a way that its links can be repeatedly pivoted to and from predetermined angular positions relative to each other.
Still another object of this invention is to provide the above outlined link chain with novel and improved noise-reducing means and with novel and improved means for distributing friction between neighboring plates of composite links of which the chain is assembled.
A further object of the invention is to provide the links of the improved chain with plates capable of confining the elements of coupling units between neighboring composite links in a novel and improved way, particularly in a manner to confine the elements to predetermined movements which cause a small amount of wear and which invariably take place between preselected portions of the surfaces of such elements and the internal surfaces of neighboring composite links.
Another object of the invention is to provide a novel and improved method of assembling the plates of composite links and the elements of coupling units for pairs of neighboring links in a manner such that the extent of friction between neighboring plates and/or the extent of play between neighboring plates can be determined and maintained with a heretofore unknown degree of accuracy and predictability.
An additional object of the invention is to provide a novel and improved method of confining the pin-shaped elements of coupling units for the links of link chains in the windows of plates of which the links consist.
Still another object of the invention is to provide a lighweight link chain which can be utilized as a superior substitute for existing link chains in existing types of continuously variable transmissions and/or other devices or apparatus or machines which employ or can employ link chains.
One feature of the present invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links. The links of each pair are movable to and from predetermined positions of at least substantial linear alignment with each other and each such link can include a stack or pile of registering plates. The link chain further comprises a plurality of coupling units, one for each pair of links and each serving to articulately connect the links of the respective pair to each other. Each such coupling unit preferably includes one, two or at least two (preferably two) adjacent coupling elements (e.g., substantially pin-shaped non-circular coupling elements), and the link chain further comprises at least one antijam (i.e., blockage preventing or obstruction preventing or interference preventing) device for each pair of links; each such device can include means for preventing movements of the respective pair of links to second (i.e., other than predetermined) positions from which the links are incapable of moving (or not readily movable) to their respective predetermined positions. Such link chains are much less likely to obstruct proper or optimum operation of a transmission than link chains which are not equipped with antijam devices.
Another feature of the invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links each of which includes a stack of plates. At least one of the links has a pitch of at least 9 mm (as used herein, the pitch is indicative of the spacing of the links from center to center; reference may be had, for example, to column 4 in the specification of U.S. Pat. No. 5,427,583 granted Jun. 27, 1995 to Wolf for xe2x80x9cLOW-NOISE, TRIPLE SIDE BAR SPROCKET CHAIN FOR INFINITELY VARIABLE TRANSMISSIONxe2x80x9d), and the link chain further comprises a plurality of coupling units, one for each pair of links and each articulately connecting the respective pair of neighboring links for pivotal movement relative to each other in clockwise and counterclockwise directions. Each coupling unit includes at least two coupling elements which are adjacent each other, and the improved link chain further comprises at least one means for limiting the pivotability of the at least one link and a neighboring link in at least one of the clockwise and counterclockwise directions to an acute angle, e.g., to an angle of less than 30xc2x0 and often or preferably less than 27xc2x0.
A further feature of the instant invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links. The links of each pair are movable to and from predetermined positions relative to each other and each link preferably comprises a stack of plates, e.g., two or more plates which are or which can be identical with each other and which accurately overlap or overlie each other. The improved link chain further comprises a plurality of coupling units, one for each pair of links and each articulately connecting the respective pair of links to each other for clockwise and counterclockwise pivotal movement to and from the respective predetermined positions. Each coupling unit includes at least two adjacent coupling elements which are angularly movable relative to each other and relative to the respective pair of links to and from preselected positions, and the link chain further comprises at least one position restoring device which includes means for confining the coupling elements of at least one of the coupling units to the preselected positions upon completion of movement of the corresponding pair of links to and from the respective predetermined positions.
An additional feature of our invention resides in the provision of a link chain having an inner side (i.e., that side which is surrounded by the chain links) and an outer side and comprising a plurality of pairs of neighboring composite links. The links of each pair are pivotable relative to each other and each link includes a stack of elongated plates each having a first end and a second end, as seen in the (forward and rearward) directions of movement of the chain. The chain further comprises a plurality of coupling units, one for each pair of neighboring links and each articulately connecting the respective pair of links to each other. Each coupling unit includes at least two adjacent parallel pin-shaped non-circular coupling elements and at least one of the elongated plates has an outline provided with projections disposed at one of its ends at one side (i.e., the inner side or the outer side) of the chain. Each such projection can serve a single purpose (e.g., to limit the extent of pivotal movement of two links of a pair of links in the clockwise or counter-clockwise direction) or two or more different purposes.
Still another feature of the invention resides in the provision of a link chain having an inner side and an outer side and comprising a plurality of pairs of neighboring composite links. The links of each pair are pivotable relative to each other and each link includes a stack of elongated plates. The improved chain further comprises a plurality of coupling units, one for each pair of links and each pivotably connecting the respective pair of links to each other. Each coupling unit includes at least two adjacent coupling elements and at least some of the plates have elongated windows extending lengthwise between the first and second end portions of the respective elongated plates. The end portions of each plate are different from each other, at least at the inner side of the chain and at least in regions adjacent the ends of the respective windows. The coupling elements extend through the windows of the respective plates.
A further feature of the invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links. The links of each pair are pivotable relative to each other and each link includes a stack of preferably accurately aligned plates. The chain further comprises a plurality of coupling units, one for each pair of links and each pivotably connecting the links of the respective pair with each other. Each coupling unit includes at least two adjacent coupling elements and at least some of the plates have windows for the respective coupling elements. At least some of the coupling elements are rockable about axes which are normal to the respective plates and such coupling elements have rounded external surfaces contacting rounded internal surfaces of the respective plates in their windows. The ratio of the radii of curvature of the internal surfaces to the radii of curvature of the external surfaces is preferably less than ten, preferably less than five. A presently preferred ratio is two or close to two.
A further feature of our invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links. The links of each pair are pivotable relative to each other and each link includes a stack of plates. The link chain further comprises a plurality of coupling units, one for each pair of links and each pivotably connecting the respective links to each other. Each coupling unit includes at least two adjacent coupling elements and at least some of the plates have windows for the respective coupling elements. At least one of the coupling elements is rockable relative to the respective plates and has an external surface whichxe2x80x94under predetermined circumstances of use of the chainxe2x80x94contacts first portions of internal surfaces of the respective plates in the corresponding windows. The internal surfaces further include second portions and, when the chain is in actual use, the stresses being applied to the second portions of the internal surfaces exceed the stresses being applied to the first portions of such surfaces.
Another feature of the present invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links. The links of each pair are pivotable relative to each other and each link includes a stack of plates. The link chain further comprises a plurality of coupling units, one for each pair of links and each pivotably connecting the respective pair of links to each other. Each coupling unit includes at least two adjacent coupling elements and at least some of the plates have windows for the respective coupling elements. Each window has two sections each of which is traversed by the coupling elements of a coupling unit and each window further includes a constriction for each of its sections. The constrictions are adjacent the respective sections of the windows. At least one coupling element in at least one of the window sections contacts the plates adjacent the respective restriction.
An additional feature of the invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links each of which includes or consists of a stack of plates. The chain further comprises a plurality of coupling units, one for each pair of links and each articulately connecting the respective pair of links to each other. Each coupling unit includes a plurality of adjacent elongated coupling elements and the link chain further comprises means for limiting the extent of movability of at least some of the plates lengthwise of the respective coupling elements, namely for preventing any movements of the plates lengthwise of the respective coupling elements or for ensuring that movements of the plates lengthwise of the respective coupling elements are maintained within a preselected range.
For example, the aforementioned limiting means can include resilient means constructed, arranged and installed to yieldably oppose movements of the plates of at least one of the links lengthwise of at least one coupling element of the respective coupling unit.
In accordance with one presently preferred specific embodiment, the improved link chain comprises a plurality of pairs of neighboring composite links each of which includes a stack of overlapping plates, and a plurality of coupling units, one for each pair of links and each articulately connecting the respective pair of links to each other. Each coupling unit includes a plurality of adjacent elongated coupling elements extending through registering windows provided in the stacks of plates of the respective pairs of links, and the link chain further comprises means for limiting the extent of play (if any) between the plates of stacks which form part of at least one pair of neighboring links to not more than 0.2 mm.
A further feature of the invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links each of which includes a stack of plates, and a plurality of coupling units, one for each pair of links and each articulately connecting the links of the respective pair to each other. Each coupling unit includes at least two adjacent elongated coupling elements extending through windows which are provided in the stacks of plates of the respective pairs of links, and the link chain further comprises means for limiting the extent of movability of the stacks of plates of at least one pair of links lengthwise of the respective coupling elements. The limiting means comprises stops provided on at least one coupling element traversing the plates of the at least one pair of links, and the stops are spaced apart from each other a predetermined distance which at least matches the actual combined thickness of the stacks of plates which are traversed by the at least one coupling element. In other words, the method of assembling such chain includes the step of actually measuring the combined thickness of the stacks of plates to be traversed or being traversed by the at least one coupling element.
An additional feature of the invention resides in the provision of a link chain which comprises a plurality of pairs of neighboring composite links. The links of each pair are pivotable relative to each other and each link includes a stack of plates. The link chain further comprises a plurality of coupling units, one for each pair of links and each articulately connecting the respective pair of links to each other. Each coupling unit includes a plurality of coupling elements extending through windows which are provided in the plates, and the link chain further comprises means for limiting the extent of pivotability of the links of at least one pair of links relative to each other. The limiting means includes a projection provided on at least one plate of at least one stack forming part of the at least one pair of links and abutting one coupling element of the coupling unit at the at least one pair of links in at least one predetermined angular position of the links of the at least one pair of links relative to each other.
The coupling unit at the at least one pair of links is not or need not be identical with the coupling unit for the at least one pair of links; such coupling units can be adjacent each other.
Another feature of our present invention resides in the provision of a transmission, such as a continuously variable transmission in the power train of a motor vehicle. The transmission comprises adjustable rotary driving and driven pulleys (preferably adjustable pulleys of the type disclosed, for example, in commonly owned U.S. Pat. No. 5,711,730 granted Jan. 27, 1998 to Friedmann et al. for xe2x80x9cTORQUE MONITORING APPARATUSxe2x80x9d), and a torque transmitting link chain which is trained over the pulleys and includes a plurality of pairs of neighboring composite links and a plurality of coupling units, one for each pair of links and each articulately connecting the links of the respective pair to each other. Each coupling unit includes at least two adjacent coupling elements and the link chain further comprises an antijam device for at least one pair of links. Such antijam device can comprise means for preventing movements of the links of the at least one pair to positions from which the links are incapable of reliably moving to positions of at least substantial linear alignment with each other.
The link chain can further comprise at least one means for limiting the pivotability of the links of the at least one pair from the positions of at least substantially linear alignment with each other through a predetermined maximum angle as well as means for maintaining the chain in an operative condition in each of a predetermined number of adjustments of the pulleys.
Another feature of the present invention resides in the provision of a link chain which comprises a plurality of pairs of composite links each of which has a first end and a second end. The links of at least one of the pairs of links respectively include first and second stacks of elongated plates; the plates of one of the stacks have first lengths and the plates of the other stack have second lengths different from the first lengths. The link chain further comprises coupling units each having a plurality of coupling elements; each such unit articulately connects one end of one link of a pair of links with one end of the other link of such pair.
Still another feature of the invention resides in the provision of a link chain which comprises a plurality of pairs of chain links each of which includes a stack of plates. The plates of one link which forms part of at least one of the pairs of links have a first chain pitch and the plates of the other link forming part of such at least one pair of links have a different second chain pitch. The link chain further comprises means for articulately connecting the plates of each pair of plates with one another.
Another link chain which is constructed and assembled in accordance with the present invention can comprise pairs of chain links and means for pivotally coupling the links of each pair to each other. Each link comprises a stack of elongated plates having first and second ends and the plates of at least one link of at least one pair of links have projections at one of their ends. The links of the at least one pair are pivotable relative to each other from first positions of at least substantial alignment with each other to and from second positions which are offset through a predetermined angle relative to the first positions. The projections engage abutment means of the chain in the second positions of the links of the at least one pair of links.
The abutment means can form part of the coupling means.
The plates of at least one link of the at least one pair of links can have first lengths, and the plates forming part of the other link of the at least one pair of links can have second lengths different from the first lengths.
Furthermore, the plates of the at least one link of the at least one pair of links can have first chain pitches, and the plates forming part of the other link of the at least one pair of links can have second chain pitches different from the first chain pitches.
The abutment means can have a first profile and the projections can have a second profile which is complementary to the first profile.
In accordance with another feature of the present invention, the improved link chain can comprise a plurality of pairs of chain links each of which includes a stack of elongated plates, and means for pivotably coupling the links of the pairs of links to each other. The plates of at least one of the links can exhibit a plurality of first characteristics including first lengths and first pitches p1, and the plates of at least one other link can exhibit a plurality of second characteristics including second lengths and second pitches p2. At least one of the first characteristics is different from at least one of the second characteristics, and the chain links of at least one pair of links are pivotable relative to each other through a first maximum angle xcex1max1, the chain links of at least one other pair of links are pivotable relative to each other through a different second maximum angle xcex1max2, and the ratio of such angles and of the pitches satisfies the equation       α          max      ⁢              xe2x80x83            ⁢      2        ≧            p2      p1        *                  α                  max          ⁢                      xe2x80x83                    ⁢          1                    .      
The angle xcex1max1 is or can be between 15xc2x0 and 25xc2x0.
A further feature of the invention resides in the provision of a link chain having an inner side and an outer side and comprising a plurality of pairs of links each including a stack of plates. The chain further comprises means for pivotably coupling the links of the pairs of links to each other. The links of each pair are respectively pivotable relative to each other through first and second angles toward the outer side and toward the inner side of the chain, and the latter further comprises means for limiting the pairs of links to pivotal movements through the first and second angles. Such limiting means includes first abutments provided on at least some of the links and arranged to determine the first angles, and second abutments provided on at least some of the links and arranged to determine the second angles.
The limiting means can further include portions of the coupling means.
The last mentioned link chain can further comprise means for preventing jamming of the pairs of links upon pivoting through the first angles, and means for preventing jamming of the pairs of links upon pivoting through the second angles.
In accordance with a further feature of the invention, the improved link chain comprises a plurality of pairs of links each of which includes at least one plate. The links include first, second, third and fourth links and the link chain further comprises first, second and third coupling units which movably connect the first and second, the second and third and the third and fourth links to each other. Each coupling unit includes at least one coupling element and the plates have windows through which the respective coupling elements extend. The coupling elements are arranged to move during movement of links of the respective pairs of links relative to each other.
The links of the pairs of links are pivotable relative to each other and the coupling elements are arranged to turn during pivoting of the links of the respective pairs relative to each other.
At least one of the coupling elements can be received in at least one of the respective windows with a play of less than 0.1 mm.
The external surfaces of the coupling elements can contact the plates of the respective pairs of links in predetermined positions of the respective pairs of links relative to each other.
The external surface of at least one coupling element can be arranged to contact an internal surface of at least one plate forming part of one of the respective pair of links at the outer side of the chain.
Furthermore, the external surface of at least one coupling element can be arranged to contact the internal surface of at least one plate forming part of one of the respective links at the inner side of the chain.
The arrangement can be such that the links are movable lengthwise of the chain in at least one direction in actual use of the chain and the external surface of at least one coupling element can be arranged to contact the internal surface of at least one plate of the respective pair of links at the inner side of the chain and as seen in the at least one direction.
The windows of the plates can be provided with constrictions and the external surface of at least one of the coupling elements can be arranged to contact the internal surface of at least one plate of at least one of the respective pair of links in the region of the respective constriction.
The plates can be provided with at least partially rounded internal surfaces bounding the respective windows, and the coupling elements can be provided with at least partially rounded external surfaces arranged to contact the respective internal surfaces in predetermined positions of the respective pairs of links relative to each other. The radii of curvature of the rounded internal surfaces can greatly exceed the radii of curvature of the external surfaces; for example, the radius of curvature of each internal surface can be up to ten times the radius of curvature of an external surface. It is often preferred to select the radii of curvature in such a way that the radius of curvature of each internal surface in twice the radius of curvature of an external surface.
It is also within the purview of the invention to construct and assemble the Improved link chain in such a way that it comprises a plurality of pairs of links each having a stack of at least substantially registering plates, and means for pivotably coupling the links of the pairs of links to each other. The coupling means comprise elongated coupling elements extending through windows provided in the stacks of plates of the respective pairs of links and the chain further comprises means for biasing the plates of the pairs of links lengthwise of the respective coupling elements. The biasing means has a spring gradient in the range of between about 0.2 N/mm and 200 N/mm, preferably between about 2 N/mm and 10 N/nm.
The biasing means is arranged to eliminate play between the plates of the stacks of plates being traversed by the coupling elements.
A link chain which embodies another feature of the invention can comprise a plurality of pairs of links each including a stack or pile of plates which are provided with at least partially registering windows, and a plurality of coupling units each of which is arranged to pivotably couple a pair of links to each other for movement toward an outer side and an inner side of the link chain. Each coupling unit includes at least one elongated coupling element having spaced-apart cam faces and extending through the windows of plates forming part of the respective pair of links. The stacks through which the coupling elements extend include first outer plates disposed at a predetermined distance from one cam face of the respective coupling element and second outer plates disposed at the same predetermined distance from the other cam face of the respective coupling element.
Another link chain which embodies our invention and is particularly suited for use in a continuously variable transmission comprises a plurality of pairs of links each of which includes a stack of plates having at least partially registering windows, and a plurality of coupling units, one for each pair of links and each including at least one pin extending through the windows of stacks of plates of the respective pair of links. Such chain further comprises pairs of stops provided on the pins and flanking the respective stacks of plates. The stops of each pair are spaced apart from each other by a distance exceeding by a predetermined value, including zero, the measured combined thickness of the stacks of plates which are traversed by the respective pin. Thus, one actually measures the combined thickness of the stacks of plates which are traversed by a pin, and one thereupon selects the distance between the stops of the respective pair in dependency upon the measured combined thickness.
Another improved link chain comprises a plurality of pairs of links each having at least one apertured plate, and a plurality of coupling units, one for each pair of links and each including a non-circular pin extending through the apertured plates of the respective pair of links. The chain further comprises means for counteracting wobbling of plates which are traversed by at least one of the pins and means for permitting limited pivoting of pairs of links relative to each other. The means for permitting limited pivoting can include portions of the plates and/or portions of the pins.
Thus, our improved link chain can be constructed and assembled in such a way that it embodies single features which distinguish it from conventional link chains, or two or more novel features (such as the aforementioned means for counteracting wobbling of the plates and the means for permitting limited pivoting of the links of each pair relative to each other).
A continuously variable transmission which can be utilized in the power train of a motor vehicle and which embodies our present invention can comprise adjustable driving and driven pulleys and a link chain which is trained over the pulleys and includes a plurality of pairs of neighboring composite links. The links of each pair are movable to and from predetermined positions of at least substantially linear alignment with each other and each link includes a stack of plates. The chain further comprises a plurality of coupling units, one for each pair of links and each articulately connecting the links of the respective pair to each other. Each coupling unit includes at least two adjacent coupling elements in the form of pins, shafts or the like and the chain further comprises at least one antijam device for each pair of links. Each antijam device comprises means for preventing movements of links of the respective pair of links to second positions from which the links are incapable of moving to their respective predetermined positions.
A further feature of the invention resides in the provision of a method of assembling a link chain, particularly for use in a continuously variable transmission. The method comprises the steps of articulately connecting pairs of composite elongated links to each other for pivotal movement about axes extending transversely of the respective elongated links, and at least one of a plurality of additional steps such as limiting the extent of pivotability of the links of at least one of the pairs of links relative to each other and/or counteracting the tendency (if any) of links of at least one of the pairs of links to wobble with respect to each other. The connecting step can include articulately connecting pairs of identical, similar or dissimilar links to each other.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved link chain itself, however, both as to its construction and the modes of assembling, installing and utilizing the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.